1. Field of Invention
The present invention relates to cutters of objects which are at least generally circular in cross-sectional area and in which the cutter blade(s) moves with respect to the object, and more particularly, in its most preferred embodiment, to a cutter assembly system for pipe casings and the like.
2. Prior Art
There is a large body of prior patent art directed to various types of cutters for pipes.
A collection of prior patents disclosing various pipe cutters in which there are one or more moveable cutters which move about the pipe for the cutting thereof is presented below:
______________________________________ Patentee(s) Patent No. Issue Date ______________________________________ A. W. Shaw, et al 2,842,238 May 18, 1956 J. E. Jennison 2,851,773 June 21, 1957 A. McIver 2,697,875 Dec. 28, 1954 W. E. Shultz 3,249,998 May 10, 1966 L. K. Bridges, et al 3,290,779 Dec. 13, 1966 J. A. Berberian, et al 3,456,856 July 22, 1969 Duck, et al 3,720,260 March 13, 1973 Sherer, et al 3,807,047 Apr. 30, 1974 Sherer 4,185,525 Jan. 29, 1980 ______________________________________
In these prior art devices the cutter assembly is mounted about the pipe to be cut, completely encircling and enclosing the pipe about a total of 360.degree.. In one instance, the Duck et al patent ('260), the cutter assembly is permanently mounted about the pipe string.
More typically, the prior art comprises temporarily mounted tools which encircle and enclosed the pipe for the complete 360.degree., requiring some sort of "gate" type structure to allow entry and removal of the pipe from the pipe cutting area.
For example, in the Jennison ('773) and Shaw et al ('238) patents the cutter is dividable into separable, 180.degree. parts which are assembled, joined and clamped together about the pipe during the cutting operation, and the process reversed in order to prepare the tool for the next pipe to be cut.
The Bridges et al ('779), McIver ('875), the Berberian et al ('856), Sherer et al ('525), Shultz ('998) and the Sherer et al ('047) patents use hinged sections which are moveable apart and together to open and close the cutter assembly about the pipe to be cut.
In most of the foregoing prior art the mountings for the cutter blade(s) are fixed to the basic assembly body and the entire cutter assembly (body and blades) moved about the pipe during the cutting operation.
In two of the foregoing prior art devices, the cutter blade mounting is moveably carried by the cutter assembly body and rides on a trackway with the body assembly being clamped to the pipe being cut. The moveably mounted cutter then travels 360.degree. on the trackway completely about the assembly body affixed to the pipe.
Thus the prior art approaches have required relatively cumbersome and complex assemblies to allow for the entry and removal of the object to be cut, and either required that either the entire assembly with its fixed cutter mountings be moved about the pipe or that the assembly be affixed to the pipe using a single, moveable cutter travelling the complete 360.degree. about the pipe on a trackway.
Thus, inter alia, all of these foregoing prior art cutter tool patents require a base assembly type structure which has a moveable gate type element to allow for the entry and removal of the pipe or other object being cut from within the encircling base assembly before and after the cutting process, respectively.
In contrast, the present invention utilizes a relatively simple, straight forward structure and approach in which the base assembly always has an open entry and exit area without the need for a moveable gate element and includes at least two moveable cutters annularly traveling on a trackway, neither of which move their arcuate separation distance and each of which moves at least a little over half their arcuate separation distance.